The present invention relates to an electric power consumption control system in which a total electric power consumption to be consumed by a plurality of image forming apparatuses installed in the system is controlled, so as to prevent the system from occurring an interruption of an electric power supply (hereinafter, referred to as a power shutdown, for simplicity) caused by an excessive consumption of the total electric power supplied to the plurality of image forming apparatuses.
An abrupt power shutdown tends to cause harmful influences for an apparatus concerned. Accordingly, for instance, it is necessary for an image forming apparatus, such as a digital Multi-Functional Peripheral or the like, to protect an HDD (Hard Disc Drive) for storing digital image data from a failure and/or a damage caused by the abrupt power shutdown. Further, sometimes, a jam occurrence, caused by the abrupt power shutdown during a printing operation, not only requires a cumbersome operation for removing a jammed paper sheet, but also makes a torn part of the jammed paper sheet remain in the apparatus during the removing process, or makes the apparatus inside and/or the hands of the operator contaminated by the unfixed toner image.
To overcome the abovementioned inconveniences, for instance, Tokkaihei 5-72844 (Japanese Non-Examined Patent Publication) sets forth such an apparatus that incorporates a UPS (Uninterruptible Power Supply) and reduces the electric power consumption at a minimum level when the apparatus is operated in a UPS mode (by using electric power supplied from the UPS) after an occurrence of an unexpected power shutdown so as to extend a time duration for supplying the electric power from the UPS, so that, during the abovementioned time duration, the apparatus can perform various protective operations, such as notifying the user of the occurrence of the power shutdown, ejecting a recording paper sheet in mid-course of copy processing so as not to remain it inside the apparatus, initializing a photoreceptor member so as to protect the photoreceptor member from harmful influences, storing various kinds of information into a nonvolatile memory serving as a temporal shelter so as to make it possible to resume the processing of the current job at the time of resumption of the apparatus operations after the electric power supply is restored to the normal state, and conducting shutdown operations so as to stop the electric power supply from the UPS after the abovementioned operations are completed.
Further, for instance, Tokkai 2002-297353 (Japanese Non-Examined Patent Publication) sets forth such a system that includes a plurality of image forming apparatuses, which are coupled to each other through a network in such a manner that the plurality of image forming apparatuses are controlled by bilaterally communicating with each other, so that the total electric power consumption does not exceed a predetermined threshold level, in order to prevents the plurality of image forming apparatuses from the power shutdown. Concretely speaking, when a certain image forming apparatus included in the system accepts a job instructed by a user, with the implementation priority of the job concerned. At this occasion, when the image forming apparatus concerned determines that the total electric power consumption to be consumed by all of the image forming apparatuses included in the system will exceed the predetermined threshold level if the job instructed by the user concerned is implemented, the image forming apparatus concerned instructs another image forming apparatus, which is currently performing another job having an implementation priority lower than that instructed by the user concerned, to implement the other job in a power saving mode. Receiving the abovementioned instruction from the image forming apparatus concerned, the other image forming apparatus implements the other job in a low speed mode, so as to reduce the total electric power consumption to be consumed in the system.
Although the UPS makes it possible to appropriately cope with an abrupt power shutdown as abovementioned, the UPS is very expensive. Specifically in the image forming apparatus that employs a fixing device for applying heat and pressure onto a toner image so as to fix the toner image onto the transfer material, it is necessary to employ such a UPS that has a bulk power outputting capability, due to the large amount of electric power consumed by the fixing device, and accordingly, the price of the image forming apparatus would be skyrocketed.
On the other hand, in the abovementioned system in which priorities of various jobs are compared with each other based on the implementation priority designated by the user so as to implement the low priority job in a low speed mode, since every user can freely establish the implementation priority degree of his own job at any rank, the user tends to designate it at a “high” priority rank. As a result, since most of all jobs are set to the “high” priority rank, there has arisen a problem that the arbitrating operation based on the implementation priorities designated by various users could not be achieved successfully.
Therefore, it is required to provide an image forming apparatus and an electric power consumption control system, which makes it possible to appropriately select a specific image forming apparatus to be shifted to the power saving mode, based on the implementation priority degree, in order to avoid the power shutdown of the electric power consumption control system.